NINOS is a multicenter, multinational, randomized, double-masked controlled clinical trial in which infants are randomly assigned to receive either inhaled nitric oxide or 100% oxygen. The purpose of this study is to evaluate inhaled nitric oxide as a potential therapy for term and near-term infants diagnosed with hypoxic respiratory failure, including infants with primary persistent pulmonary hypertension of the newborn, meconium aspiration, sepsis/pneumonia, hyaline membrane disease, suspected pulmonary hypoplasia, and congenital diaphragmatic hernia.